Sqorus with rounded edges?
Use the beam builder

Then in edit mode, select all and correct the normal CtrlN.

Now select one of the edges you want to bevel.

ShiftG to select similar and choose "length".

Your wanted edges are now selected.

Use CtrlB to bevel (use Numpad + or Numpad - to set the bevel depth).



Note: if you want to smooth it, click on smooth, but the result is weird, so, add an 'edge split' modifier.